Zoophytophagous predator-induced defences restrict accumulation of the tomato spotted wilt virus.

BACKGROUND: The use of zoophytophagous predators in protected crops has been widely adopted to manage pests in southern Europe. We hypothesized that plant defence responses would be induced by zoophytophagous predators and this induction could affect plant virus occurrence; the phytophagy of these predators induces plant defences similarly to that of viral infection. Therefore, we evaluated whether or not mirid predator-activated plant defences limited the accumulation of Tomato Spotted Wilt Virus (TSWV) in mechanically infected sweet pepper. RESULTS: Our results revealed TSWV accumulation in mirid-punctured plants to be significantly lower than in intact plants. This is most likely associated with the upregulation of the jasmonate acid pathway triggered by mirid phytophagy. CONCLUSION: Activation of induced defences by mirid predators has been demonstrated for the first time to limit the accumulation of TSWV in sweet pepper. This novel approach can offer new control strategies for the management of plant diseases. © 2019 Society of Chemical Industry.

Combined Use of Predatory Mirids With Amblyseius swirskii (Acari: Phytoseiidae) to Enhance Pest Management in Sweet Pepper.

The combined release of Orius laevigatus (Fieber) (Hemiptera: Anthocoridae) with Amblyseius swirskii (Athias-Henriot) (Acari: Phytoseiidae) provides effective control of sweet pepper key pests, such as thrips and whiteflies. However, the management of the aphids can still be improved. Recently, the predatory mirids Nesidiocoris tenuis (Reuter) (Hemiptera: Miridae) and Macrolophus pygmaeus (Rambur) (Hemiptera: Miridae) have been found to be effective in the control of aphids, thrips and whiteflies when tested alone. Hence, integrating one of these two mirids with A. swirskii might enhance sweet pepper pest management. In this work, we began by investigating the co-occurrence of both mirid species when released together with A. swirskii. This was compared to the standard release of O. laevigatus with A. swirskii. N. tenuis and A. swirskii were involved in a bidirectional intraguild predation (IGP). On the contrary, this interaction (IGP) was apparently unidirectional in the case of M. pygmaeus with A. swirskii and O. laevigatus with A. swirskii. Both, M. pygmaeus and O. laevigatus significantly reduced the abundance of A. swirskii. Secondly, in a greenhouse experiment, where the same release combinations were tested (either N. tenuis, M. pygmaeus or O. laevigatus combined with A. swirskii), IGP seemed to be neutralized. Mirids with A. swirskii significantly suppressed thrips, whitefly, and aphid infestations. Contrarily, the combined use of O. laevigatus with A. swirskii did not reached a satisfactory control for aphids, despite the reduction in thrips and whitefly densities. Therefore, our results suggest that the use of mirids combined with A. swirskii could result in more efficient and robust biological control programs in sweet pepper crops.

Zoophytophagous mirids provide pest control by inducing direct defences, antixenosis and attraction to parasitoids in sweet pepper plants.

BACKGROUND: In addition to their services as predators, mirid predators are able to induce plant defences by phytophagy. However, whether this induction occurs in sweet pepper and whether it could be an additional benefit to their role as a biological control agent in this crop remain unknown. Here, these questions were investigated in two model insects, the mirids Nesidiocoris tenuis and Macrolophus pygmaeus. RESULTS: Plant feeding behaviour was observed in both N. tenuis and M. pygmaeus on sweet pepper and occupied 33% and 14% of total time spent on the plant, respectively. The punctures caused by mirid plant feeding induced the release of a blend of volatile organic compounds (VOCs) which repelled the herbivore pests Frankliniella occidentalis and Bemisia tabaci and attracted the whitefly parasitoid Encarsia formosa. The repellent effect on B. tabaci was observed for at least 7 days after initial exposure of the plant to N. tenuis, and attraction of E. formosa remained functional for 14 days. CONCLUSION: Plant defences induced by the feeding of mirid predators, their subsequent effects on the behaviour of both pests and natural enemies, and the persistence of these observed effects open the door to new control strategies in the sweet pepper crop. Further application of this research is discussed, such as the vaccination of plants by zoophytophagous mirids in the nursery before transplantation. © 2017 Society of Chemical Industry.